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Sharpening planer/jointer blades

Some years ago we had two sharpening businesses in this area but both are now gone. Iíve used a few of the home brewed methods for resharpening these blades but they are not completely satisfactory. Looking at the various jigs on the internet, it seemed that hardly any were able to turn out anything near to a professional job while most appeared somewhat crude. So, after some frustration in searching, I decided to tackle the job head on and build a good jig that could guarantee a first rate job.

The method I chose is similar in concept to the one used by one of the local pros who had the Belsaw machinery. The only thing I really recalled in detail was the movement of the blade against the grinding wheel, so I started with that. My low speed grinder is bolted to a workbench and had room for the jig to be located properly and removed when not in use. The photos show the base which is temporarily screwed in position to the bench in the alignment that allowed the blade to be moved along the edge of the wheel similar to the Belsaw machine. A fence is secured on the far end to the base and can be moved horizontally in small increments to adjust the grinding depth on the blade.

The blade carriage is the most critical part and holds the blade at the proper bevel angle to the edge of the grinding wheel. ďProperĒ in this sense is what I thought it should be to duplicate the existing bevel on the blades. A blade is clamped in place by the knobs on the carriage and rests on the ledge as is shown in the end view. For blades of different widths, a shim can be inserted to raise the blade if necessary. The grinding angle changes very little for small vertical movement on the large 8Ē wheel so Iíve not found that necessary so far. Sliding surfaces of base, fence and carriage are machined flat and waxed to make movement accurate and easy.

In use, the adjustable knob to the left on the base is turned to bring the blade up to just touching the wheel and the other knob tightens the fence in position but still allows it to move with force from the adjusting knob. Minor rotation of the adjustment wheel advances the blade toward the wheel and the carriage is run back and forth a few times for each incremental adjustment. If a cooling air flow were installed on the point of grinding, the job could go much faster with more material being taken off with larger increments but I have not added that refinement. Actually it is kind of fun to see the near perfect finished blade to come off the jig. The very fine cuts taken in this way produce a finish that has a brighter shine than from pro jobs but I donít know if that has any advantage or not.
The last photo shows three finished blades as they came off the jig. They look pretty good to me and are certainly sharp and true in perfect alignment with each other. If a back bevel is desired, which is recommended to toughen the edge, it can be done by hand on wet/dry paper as is the usual way.
A few sets of blades from my planer and jointer plus a couple of friends machines have been done but I have no plans to go into the business. In any case, there is no longer a reason to make excuses for the dull or gapped blades on my machines and a fresh set is always available.

Re: Sharpening planer/jointer blades

Nice jig, I'm working on a similar line for the planer, but apart from the planer blades and a paper guillotine blade, I need a hollow ground concave edge on the Morso picture framing guillotine blades...its not just sharper, but the hollow grind repels the waste better,. Straight grind just digs in and jams. I send them to the Morso agent in UK, shipping alone is a about 50 bts each way,and the hollow grind, IF there are no chips is about 90 each knife, and they have to be matched too. And if they have been straight ground, the correction back to hollow grind is more than the knives cost.. about 250 a pair

Has to be a jig I can make and Tom's pics are more inspiration Thanks.

Re: Sharpening planer/jointer blades

Originally Posted by jonboy

Nice jig, I'm working on a similar line for the planer, but apart from the planer blades and a paper guillotine blade, I need a hollow ground concave edge on the Morso picture framing guillotine blades...its not just sharper, but the hollow grind repels the waste better,. Straight grind just digs in and jams. I send them to the Morso agent in UK, shipping alone is a about 50 bts each way,and the hollow grind, IF there are no chips is about 90 each knife, and they have to be matched too. And if they have been straight ground, the correction back to hollow grind is more than the knives cost.. about 250 a pair

Has to be a jig I can make and Tom's pics are more inspiration Thanks.

If you use a small diameter wheel on a grinder that will allow you to rotate the jig to grind more on the face, a hollow grind is doable. Of course we don't want a hollow grind on these blades because it would be too weak. That is why I use the acute angle to the side of the wheel.

Re: Sharpening planer/jointer blades

The machines I have use Tersa Heads. I had one machine converted as the disposable two sided blades a light years ahead of the standard ones.
They are self alighing and can nearly be thrown at the machine when doing the three minute blade change!
Jay

Re: Sharpening planer/jointer blades

I'm sure that new disposable blades are a big step forward. Nevertheless there are still many Luddites around that are stuck to their old iron. My old planer works well and turns out surfaced boards that are as good as I could need so it will be here until one of us dies, which is pretty much guaranteed to be me first. That is what this jig was designed for and I find it much more convenient to sharpen my own than to send them off to a pro shop. Carbide tablesaw blades are another matter and they must be mailed off. An adequate number of spare blades is the way that I've gotten around the inconvenience of down time.

Re: Sharpening planer/jointer blades

Nice setup. However for those of us that don’t have that, I take my jointer knives to Rockler and they have a Friday to Friday send out service. For installation into the cutting head, I’ve found a magnetic jig works really well.

Re: Sharpening planer/jointer blades

Originally Posted by Tom Lathrop

If you use a small diameter wheel on a grinder that will allow you to rotate the jig to grind more on the face, a hollow grind is doable. Of course we don't want a hollow grind on these blades because it would be too weak. That is why I use the acute angle to the side of the wheel.

The blades on my ancient planer are 1/2'' thick . I've been using this jig for a few years now, it gives a hollow grind which I then dress off with an oil stone.

Re: Sharpening planer/jointer blades

Half inch is far thicker than any blade I run into, Peter. Those blades would take forever to shape by hand and your nice set up appears to make quick work of it. Looking at the final shape, it appears that the edge angle on your concave grind is still as great as I get on my set up with 1/8 to 3/16 blades. A flat grind would probably remove way too much of the blade to get a good cutting angle.

As you say, very little material is removed with each pass and I'd guess that I take off well under a thousandth inch each pass. If a blade has a gap from hitting an unknown fastener or even a natural inclusion, the process takes longer for a clear edge. A coarser grit would be faster but my grinder happens to have the fine al-oxide wheel on the side I like to use as a right handed person. Works well enough so I will not change it.

Its good to see how other woodworkers dress and sharpen their blades at home. If there was still a suitable service nearby, I would have used them, but having built this jig, that will not ever be necessary again.

Re: Sharpening planer/jointer blades

I'd send my blades away and do occasionally but the pro shop likes to remove all the nicks and unfortunately I use a lot of used wood with predictable results. Perfection looses a lot of blade off the edge. I find that on my old planer I can dodge the nick by setting one of the blades a left or right. The nick doesn't show up on the job.

Re: Sharpening planer/jointer blades

I used to struggle sharpening planer and jointer knives then I learned about this nifty trick.
I use a diamond stone that takes the top layer off very fast then a few swipes with the oil stone. Taking them out of the machine and putting them back in is the time consuming part. I have one for the planer knives and one that fits the jointer knives.

I cut the notches to fit the knives on the table saw.

Just a couple passes with the diamond stone and they already look better. These sat in the planer all winter so they got a tinge of rust on em.

Just a few minutes with the diamond stone, a couple passes with the oil stone and they are ready to go back in the planer

Re: Sharpening planer/jointer blades

Sdenette's post 15 is neat and simple if you dont have to seriously grind a lot off the blade...so if you are just going to give them a lick to hone rather than sharpen why take them out of the machine at all. I can see the need to protect the bed, but a thin polyester sheet, melanex 125 micron, or the thinnest semi-rigid plastic, like double glazing acrylic held down with a couple of strips of double sided tape…..Just wondering…?

Re: Sharpening planer/jointer blades

Originally Posted by jonboy

Sdenette's post 15 is neat and simple if you dont have to seriously grind a lot off the blade...so if you are just going to give them a lick to hone rather than sharpen why take them out of the machine at all. I can see the need to protect the bed, but a thin polyester sheet, melanex 125 micron, or the thinnest semi-rigid plastic, like double glazing acrylic held down with a couple of strips of double sided tape…..Just wondering…?

A nick would take awhile to fix this way but this is how I actually sharpen them. It's much more than just a quick hone,

the knives were dull as dirt when they came out of the machine.

The course diamond stone removes the metal in a hurry so it does not take too long to do, I use a cheap oil stone to smooth out the pattern left buy the diamond but I don't bother going beyond that. By doing them all at once in the jig I don't have to worry too much about grinding them to different sizes and am less likely to put a bow in the blade.

So far it has worked very well for me for sharpening the knives.

Knock on wood but I have yet to nick one of the blades, I am pretty careful about what lumber gets put through the planer but I suppose it's only a matter of time before I find some steel or a stone in or on the timber. Then I might have to make a jig like the other guys have or just buy a new set of knives.

Re: Sharpening planer/jointer blades

as long as you don't have any nicks, there are ways to put a microbevel on both planer and jointer blades without removing them. Harry Bryan described the former in a WB article. The latter is described in a Fine Woodworking article, if I remember. I try to avoid at all costs removing my planer blades!